Medical radiation shielding system for use with a radiation source below a table

ABSTRACT

A radiation shield assembly is described, configured to block radiation emanating from a radiation source from reaching a user. Two shields are supported by a support arm, and are configured to rotate and translate relative to one another about the support arm&#39;s longitudinal axis. This allows the shield to be easily configured and reconfigured as necessary to visualize various parts of a patients body via radiography.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage under 35 U.S.C. 371 ofInternational Application No. PCT/US2018/046318 having an internationalfiling date of Aug. 10, 2018. International Application No.PCT/US2018/046318 cites the priority of U.S. provisional patentapplication No. 62/544,468, filed Aug. 11, 2017.

BACKGROUND Field

The present disclosure relates generally to radiation protectiondevices, and specifically to devices to protect medical personnel fromradiological hazards in the operating room.

Background

Recent improvements in electronics and robotics have enabled surgeons touse noninvasive microsurgical techniques to replace numerous openincision techniques. When the site of surgical intervention is not opento the operating room, the site must still be visualized in order toadequately guide and control the instruments. This can be accomplishedby radiological monitoring, the most common example of which is X-raymonitoring. During the procedure an X-ray generator is positioned on oneside of the patient to emit X-rays to the surgical site (this isgenerally below the patient, although the position of the X-raygenerator can be varied as necessary). An X-ray intensifier ispositioned to receive the emitted X-rays after they have passed throughthe surgical site, to convey image data to a monitor or other means topresent a visual image to the surgeon.

Although these microsurgical techniques represent a vast improvementover previous open body techniques in terms of trauma to the patient,recovery time, and risk of infection, the constant radiologicalmonitoring exposes everyone involved to more radiation than was requiredusing the old techniques. This is a minor concern for the patient, whois likely to undergo only a small number of such surgeries in alifetime. However, the professional medical staff who perform theseprocedures have much more frequent exposure, and the cumulative exposurecould easily exceed safe limits unless the staff are somehow protected.

Previous attempts to solve these problems have serious limitations.Placing heavy shielding around the patient can block the radiation fromreaching the medical staff. However, the medical staff still need accessto the patient's body, so complete shielding is impractical; because thehuman body is transparent to X-rays (“radiolucent”), X-rays can shinethrough the patient's body and expose the medical staff. Any surgerycarries with it a risk of life-threatening complications that wouldrequire the medical staff to have immediate access to the patient'sbody. Heavy shields around the patient's body are bulky and difficult tomove, which can prevent emergency access by the medical staff to thepatient in such a situation.

Another attempt to protect medical staff during such procedures hasinvolved worn shielding, or basically radiation “armor.” These havetaken the form of lead vests, lead skirts, lead thyroid collars, leadedacrylic face shields, leaded acrylic glasses, and “zero gravity” leadedsuits. Radiation armor has a serious disadvantage: it must be ofsignificant mass to block X-rays (generally containing lead, a verydense metal), and it is heavy to wear. Wearing heavy radiation armorrapidly fatigues even a physically fit wearer, and with chronic use cancause orthopedic disorders. When using radiation armor to protectmedical staff from X-rays, one health hazard is simply being exchangedfor another.

Glasses and face shields by themselves might be of a manageable weight,but alone they protect only a tiny portion of the body.

“Zero gravity” suits are leaded body suits that are suspended by a rigidmetal frame. The frame is mounted on some supporting structure, such asthe floor or ceiling. As a result the wearer does not support the suitwith his or her body. This type of suspended armor has additionaldrawbacks. It leaves the wearer's hands and lower arms uncovered andunprotected to allow the wearer to engage in fine manual work. It limitsthe wearer's range of bodily movement to movements that can beaccommodated by the frame, often preventing the wearer from bending overor sitting. They use a static face shield that prevents the wearer frombringing anything close to the face, for example for visual scrutiny.Suspended armor systems are extremely expensive due to their complexityand due to material costs, currently costing about $70,000 per suit.

Another form of radiation armor is the mobile “cabin,” that is aradiopaque box on wheels in which the user stands. The user is able topush the cabin from place to place while inside. The cabin has arm portsat a certain height and a visually transparent portion at a certainheight. As a result the user's hands and face cannot be repositioned orreoriented much, for example to stand or lean over. It also uses astatic face shield that prevents the wearer from bringing anything closeto the face, for example for visual scrutiny.

There is therefore a need in the art for a means to shield medical stafffrom X-rays to which a patient must be exposed that does not encumberthe user's body, allows access to the patient's body, and can be rapidlyreconfigured if necessary.

SUMMARY

The present disclosure describes a radiation shield assembly thataddresses the problems described above by interposing a barrier betweenan operating area and an area containing medical personnel. Working inconjunction with the shield curtain hanging below the operating table,the shield assembly significantly reduces the radiation that reaches thepersonnel area both directly from the radiation generator and indirectlythrough the patient's radiolucent body, allows access to the patient'sbody, allows complete freedom of movement on the part of the user, andcan be easily reconfigured as needed. The shield assembly generallycomprises two shield structures supported by a support member such as amast or suspension arm. Each shield structure has at least one generallyvertical shield, and the two vertical shields can be rotated relative toone another about the longitudinal axis of the support member andtranslated relative to one another about the longitudinal axis of thesupport member.

In a first aspect a radiation shield assembly is provided, configured toblock radiation emanating from a radiation source. In the first aspectthe assembly comprises supporting means to support the assembly; firstshielding means to block radiation from the source in a firstapproximately vertical plane, fastened to the supporting means, andcomprising an appendage opening dimensioned to allow a human appendageto pass through the first shielding means; and second shielding means toblock radiation from the source in a second approximately verticalplane, fastened to the supporting means to allow the second shieldingmeans to translate and rotate along an approximately vertical axisrelative to the first shielding means.

A second aspect of the radiation shield assembly is provided, saidsecond aspect comprising: a support arm constructed to support at leastthe majority of the weight of the shield assembly, the support armhaving a longitudinal axis; a first generally planar vertical shieldfastened to the support arm, and having an opening proximate to a lowerend dimensioned to admit a human appendage; a second generally planarvertical shield translatably and rotationally connected to the supportarm to rotate about and translate along an axis that is approximatelyparallel to the longitudinal axis of the support arm; wherein the firstvertical shield, first horizontal shield, second vertical shield, secondhorizontal shield, and lower vertical shield are all radiopaque.

In a third aspect a system for shielding a user from a bottom-mountedX-ray generator while said user attends to a prostrate patientpositioned above the X-ray generator is provided, the system comprising:a table constructed to support the patient, the table having alongitudinal axis and a transverse axis; the X-ray generator positionedbelow the table; an image intensifier positioned above the table toreceive X-rays projected from the X-ray generator; a radiopaque curtainshield extending downwardly from the table on at least a first side ofthe table; and a radiation shield assembly comprising a support armconstructed to support the weight of the shield assembly and having agenerally vertical longitudinal axis, a first shield assembly fastenedto the support arm, comprising a first generally planar vertical shield,positioned proximate to the first side of the table and approximatelyparallel to the longitudinal axis of the table and an opening in thefirst vertical shield positioned above the table to allow the patient'sarm to pass through the opening; and a second shield assembly rotatablyand translationally fastened to the support arm to allow the secondshield assembly to rotate and translate about an axis approximatelyparallel to the longitudinal axis of the support arm, the second shieldassembly comprising a second generally planar vertical shield positionedabove the table; wherein the second vertical shield may be rotated aboutits axis to be approximately orthogonal to the longitudinal axis of thetable or to be approximately parallel to the longitudinal axis of thetable.

In a fourth aspect, a radiation shield assembly configured to blockradiation emanating from a radiation source is provided, the assemblycomprising: a support arm constructed to support at least the majorityof the weight of the shield assembly, the support arm having alongitudinal axis; a first generally planar vertical shield fastened tothe support arm via a first radiopaque joint; and a second generallyplanar vertical shield translatably and rotationally connected to thesupport arm via a second radiopaque joint to rotate about and translatealong an axis that is approximately parallel to the longitudinal axis ofthe support arm.

In a fifth aspect, a radiography method is provided, comprising:positioning any of the radiation shield assemblies above between apatient and a user, such that an appendage of the patient extendsthrough an appendage opening in the shield assembly; inserting a medicaldevice into vasculature of the appendage; and irradiating the patientusing a radiation generator positioned such that radiation passes atleast partially through the patient while being blocked from reachingthe user by the shield assembly.

The above presents a simplified summary in order to provide a basicunderstanding of some aspects of the claimed subject matter. Thissummary is not an extensive overview. It is not intended to identify keyor critical elements or to delineate the scope of the claimed subjectmatter. Its sole purpose is to present some concepts in a simplifiedform as a prelude to the more detailed description that is presentedlater.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. An embodiment of the shield assembly showing the first andsecond vertical shields orthogonal to one another, in which the secondvertical shield is lowered.

FIG. 2. The shield assembly shown in FIG. 1, in which the first andsecond vertical shields are orthogonal to one another, in which thesecond vertical shield is raised.

FIG. 3. The shield assembly shown in FIG. 1, in which the secondvertical shield has been rotated to be roughly parallel to the firstvertical shield.

FIG. 4. An embodiment of the shield assembly supported by a floor unit.

FIG. 5. An embodiment of the shield assembly supported by aceiling-mounted boom.

FIG. 6. An embodiment of the shield assembly supported by aceiling-mounted monorail.

FIG. 7. An embodiment of the shield assembly supported by a wall-mountedboom (wall is invisible).

FIG. 8. An embodiment of the shield assembly supported by a supported bya wall-mounted monorail (wall is invisible).

FIG. 9. An embodiment of the shield assembly having a sixth shield.

FIG. 10. A perspective view of an embodiment of the shielding systemincluding an operating table, X-ray generator, and X-ray imageintensifier. A patient is shown in an exemplary position.

FIG. 11. A front view of the embodiment of the shielding system in FIG.10.

FIG. 12. Illustration of sensor positioning on an exemplary shieldduring dosimetry testing.

FIG. 13. Illustration of sensor positioning on a lead apron duringdosimetry testing.

FIG. 14. Illustration of sensor positioning on shield during uniformitytesting.

FIG. 15. Illustration of sensor results on shield in uniformity testing.

FIG. 16. An embodiment of the shield assembly comprising a flexibleradiopaque member on the bottom of the first shielding means, andshowing a pneumatic piston for raising and lowering the secondhorizontal shield.

FIG. 17. An embodiment of the shielding system including an operatingtable, X-ray generator, and X-ray image intensifier showing a radiopaquedrape below the operating table.

DETAILED DESCRIPTION A. Definitions

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art of this disclosure. It will be furtherunderstood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the specification andshould not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein. Well known functions or constructions maynot be described in detail for brevity or clarity.

The terms “about” and “approximately” shall generally mean an acceptabledegree of error or variation for the quantity measured given the natureor precision of the measurements. Typical, exemplary degrees of error orvariation are within 20 percent (%), preferably within 10%, and morepreferably within 5% of a given value or range of values. For example,the terms “approximately parallel” or “approximately vertical” refer toan angle within an acceptable degree of error or variation from trueparallel or vertical, such as within 45, 25, 20, 15, 10, or 1° of trueparallel or vertical. Numerical quantities given in this description areapproximate unless stated otherwise, meaning that the term “about” or“approximately” can be inferred when not expressly stated. Claimednumerical quantities are exact unless stated otherwise.

It will be understood that when a feature or element is referred to asbeing “on” another feature or element, it can be directly on the otherfeature or element or intervening features and/or elements may also bepresent. In contrast, when a feature or element is referred to as being“directly on” another feature or element, there are no interveningfeatures or elements present. It will also be understood that, when afeature or element is referred to as being “connected”, “attached”,“fastened”, or “coupled” to another feature or element, it can bedirectly connected, attached, fastened or coupled to the other featureor element or intervening features or elements may be present. Incontrast, when a feature or element is referred to as being “directlyconnected”, “directly attached”, “directly fastened”, or “directlycoupled” to another feature or element, there are no interveningfeatures or elements present. Although described or shown with respectto one embodiment, the features and elements so described or shown canapply to other embodiments.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well (i.e., at least one of whatever the article modifies),unless the context clearly indicates otherwise.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another when theapparatus is right side up as shown in the accompanying drawings.

Terms such as “at least one of A and B” should be understood to mean“only A, only B, or both A and B.” The same construction should beapplied to longer list (e.g., “at least one of A, B, and C”). Incontrast, terms such as “at least one A and at least one B” should beunderstood to require both A and B.

The terms “first”, “second”, “third,” and the like are used herein todescribe various features or elements, but these features or elementsshould not be limited by these terms. These terms are only used todistinguish one feature or element from another feature or element.Thus, a first feature or element discussed below could be termed asecond feature or element, and similarly, a second feature or elementdiscussed below could be termed a first feature or element withoutdeparting from the teachings of the present disclosure.

The term “consisting essentially of” means that, in addition to therecited elements, what is claimed may also contain other elements(steps, structures, ingredients, components, etc.) that do not adverselyaffect the operability of what is claimed for its intended purpose asstated in this disclosure. This term excludes such other elements thatadversely affect the operability of what is claimed for its intendedpurpose as stated in this disclosure, even if such other elements mightenhance the operability of what is claimed for some other purpose.

It is to be understood that any given elements of the disclosedembodiments of the invention may be embodied in a single structure, asingle step, a single substance, or the like. Similarly, a given elementof the disclosed embodiment may be embodied in multiple structures,steps, substances, or the like.

B. Radiation Shield Assembly

A radiation shield assembly 100 is provided, configured to blockradiation emanating from a radiation source and supported by a supportmeans 145 to support the assembly 100. As shown in FIGS. 1-3, a firstshielding means 105 is positioned in a first approximately verticalplane. The first shielding means 105 is fastened to the support means145, and has an appendage opening 110 dimensioned to allow a humanappendage to pass through the first shielding means 105. This givesaccess to the patient's arm (or alternatively the leg or torso) for theintroduction of a medical device (such as an arthroscopic instrument)via the patient's vasculature.

A second shielding means 115 is positioned in a second approximatelyvertical plane, fastened to the support means 145, to allow the secondshielding means 115 to translate and rotate along an approximatelyvertical axis relative to the first shielding means 105. The secondshielding means 115 can thus be raised, lowered, or swung relative tothe first shielding means 105 if necessary to gain access to the patient(compare FIGS. 1-3).

To protect the medical staff from radiation shining through theappendage 110, a third shielding means 120 may be positioned to blockradiation from the appendage opening 110 in a first approximatelyhorizontal plane that is approximately orthogonal to the first verticalplane. The third shielding means 120 may be fastened to the firstshielding means 105 such that the third shielding means 120 translatesand rotates with the first shielding means 105. In other words, thefirst 105 and third shielding means 120 may be static to one another inat least one configuration of the assembly 100 (although in someembodiments they might be mobile in at least one degree of freedomrelative to the support arm 150 or other parts of the assembly 100).Additional (or alternative) protection may be provided in the form of aflexible radiopaque member on the bottom of the first shielding means105. In an alternative embodiment of the shield assembly 100 a flexibleradiopaque member 220 is used in place of the third shielding means 120,to intercept radiation emanating through the appendage opening 110.Examples of such flexible radiopaque members 220 include a shroud, asleeve, a curtain, and one or more leaves of an iris port. They may beconstructed from any suitable flexible and radiopaque material.

A fourth shielding means 125 may be positioned in a second approximatelyhorizontal plane. The second horizontal plane is approximatelyorthogonal to the second vertical plane. The fourth shielding means 125is fastened to the second shielding means 115 such that the fourthshielding means 125 translates and rotates with the second shieldingmeans 115, for example along the support means 145. Additionalprotection may be provided in the form of a flexible radiopaque shroudon the bottom of the fourth shielding means 125. In an alternativeembodiment of the shield assembly 100 a flexible radiopaque shroud isused in place of the fourth shielding means 125.

A fifth shielding means 135 may be present, positioned in a thirdapproximately vertical plane that is approximately orthogonal to thesecond approximately vertical plane and to the second approximatelyhorizontal plane, connected to the second shielding means 115 such thatthe fifth shielding means 135 translates and rotates with the secondshielding means 115, and extending downward.

Some embodiments of the shield assembly 100 include a sixth shieldingmeans 140, positioned in a fourth approximately vertical plane,connected to the first shielding means 105 such that the sixth shieldingmeans 140 extends downward. The fourth approximately vertical plane maybe approximately parallel to the first vertical plane. The sixthshielding means 140 may be positioned to protect the user's lower bodyfrom radiation. The sixth shielding means 140 may take any of numeroussuitable forms, including one or more of a generally planar shield, aflexible drape, and an extension of the first shielding means 105.

The first 105 and second shielding means 115 may be configured to swingabout a common axis, like a hinge (compare FIGS. 1 and 2). The axis maybe the longitudinal axis of the support means 145, for example. In otherembodiments, the first 105 and second shielding means 115 may each swingabout each of two separate axes, in which said axes are approximatelyparallel to each other. In some such embodiments, the axes may both beapproximately parallel to the longitudinal axis of the support means145. By analogy, the first 105 and second shielding means 115 areenabled to swing relative to each other like the back and front coversof a book. In some embodiments the first 105 and second 115 shields arecapable of assuming relative positions of about 180° from one another,such that they are approximately parallel and/or collinear when seenfrom above, Such an “open” configuration is useful to form a barrieralong the entire length of a prostrate patient. In some embodiments thefirst 105 and second 115 shields are capable of assuming relativepositions at or approaching 0° from one another, in which case they maybe in contact with one another, or in close proximity and approximatelyparallel. In some embodiments the first 105 and the second shieldingmeans 115 are configured to rotate relative to one another over an arcof at least about 90°. In some further embodiments, the first 105 andthe second shielding means 115 are configured to rotate relative to oneanother over an arc of up to about 180°, and in further specificembodiments over an arc of from about 0-180°.

The first 105 and second shielding means 115 may also be configured totranslate relative to one another, or to translate together along thesupport means 145 (compare FIGS. 1 and 2). The shield assembly 100 maycomprise a means for translating 225 at least one of the first 105 andsecond shielding means 115 along the support means 145. By way ofexample, such means for translating 225 could be an assist mechanism, acounterweight mechanism, an electric motor, a hydraulic mechanism, apneumatic mechanism, a manual mechanism, or any combination of theforegoing.

The support means 145 may be configured to allow the entire shieldingassembly 100 to translate within the operating room, relative to anoperating table 305. For example, the support means 145 could beconfigured to allow manual translation of the entire shielding assembly100, or to allow mechanical translation of the entire shielding assembly100 by means of one or more actuators. Some embodiments of the supportmeans 145 constitute a support arm 150. The support arm 150 will beconfigured to support most of the weight of the assembly 100 (if not allof it). In the illustrated embodiment in FIGS. 2 and 3 the support arm150 is an elongate steel structure, with a longitudinal axis that isgenerally vertical when the shield assembly 100 is in use. The supportarm 150 can be constructed of any material of sufficient mechanicalstrength to support the assembly 100, and could be designed by one ofordinary skill in the art. Preferably the support arm 150 is constructedfrom material that is also radiopaque to the expected frequency andintensity of radiation. For example, some embodiments of the support arm150 are opaque to X-rays at energies typical of radiology applications.

The support means 145 will be supported by the ceiling, floor, wall, oranother structure. When floor-mounted (as in FIG. 4), it can besuspended by various structures. The support means 145 could beintegrally mounted on the floor, or alternatively supported by a stand,either mobile or static.

Some embodiments of the supporting means 145 comprise an approximatelyvertical mast 155. The supporting means 145 is capable of supporting theshield assembly 100 to some extent. For example, some embodiments of thesupporting means 145 are capable of supporting the majority of theweight of the assembly 100. In further embodiments, the supporting means145 is capable of supporting about the entire weight of the assembly100, or the entire weight. The mast 155 may be supported by variousmeans. In some embodiments of the radiation shield assembly 100, themast 155 is supported by a floor stand 170. The floor stand 170 mayfurther comprise a plurality of wheels 175 to allow easy deployment andremoval of the assembly 100. In further embodiments of the system, themast 155 is suspended by an overhead boom 160 (see FIGS. 5 and 7). Theuse of an overhead boom 160 can provide easy mobility to even arelatively massive assembly 100, allowing the assembly 100 to beemplaced and removed relative to the patient quickly and easily. Variousconfigurations utilizing the boom 160 are contemplated. For example, themast 155 may be configured to rotate about the longitudinal axis of theoverhead boom 160, or to pivot relative to the overhead boom 160. Themast 155 may be capable of translating along the longitudinal axis ofthe overhead boom 160. In further embodiments of the system, theoverhead boom 160 is supported by a second mast 165. The second mast 165may in turn be supported on a wheeled floor stand 170, mounted on theceiling, or mounted on a wall. For example, the second mast 165 may besupported by a wall-mounted rail 180 or ceiling-mounted rail 185 (seeFIGS. 6 and 8); in such embodiments the second mast 165 may be capableof translating along the wall-mounted rail 180 or ceiling-mounted rail185. As another example, the second mast 165 may be supported by awall-mounted swinging arm 190 or ceiling-mounted swinging arm 195 (seeFIGS. 5 and 7). In a further embodiment, the second mast 165 may besupported by a swinging arm that is in turn supported by a wall-mountedrail 180 or ceiling-mounted rail 185, and wherein the swinging arm iscapable of translating along the wall-mounted rail 180 orceiling-mounted rail 185.

In some embodiments in which the third horizontal shielding means 120 ispresent, the first shielding means 105 and the third shielding means 120are configured to translate together vertically. For example, the firstshielding means 105 and the third shielding means 120 may be configuredto translate together along the support means 145. The degree oftranslation may be configured to optimize the shielding of the user fromX-rays while the user is standing or sitting. For example, the firstshielding means 105 may be configured to translate along such that in afirst position a top edge of the first shielding means 105 is at leastabout the height of an adult human above the floor. Taking into accountnormal human dimensions, such height could be 175 cm, 180 cm, 185 cm,190 cm, 195 cm, or 200 cm above the floor.

Similarly, the first shielding means 105 itself will be dimensioned toprovide adequate radiation protection when in position during use. Forexample, it may have a height of at least about the distance from theupper surface of an operating table 305 to an average human's fullheight. In various embodiments the first shielding means 105 has aheight of at least about the distance from the upper surface of anoperating table 305 to a height of 175 cm, 180 cm, 185 cm, 190 cm, 195cm, or 200 cm above the floor when said operating table 305 is on thefloor. A greater height has the advantage of shielding a greater areafrom X-rays, whereas a lesser height has the advantage of reduced weightand cost.

In the illustrated embodiment in the figures, the first shielding means105 is intended to be positioned roughly parallel to the long axis ofthe operating table 305, and protect a user's upper body from X-raysemitted from a point below the table 305. In the illustrated embodimentthe first shielding means 105 is a generally planar vertical shieldfastened to the support arm 150. Of course, the first shielding means105 could fulfill its function even if not exactly vertical, and couldbe designed to be inclined as necessary or desirable to customize theshielded area. Some embodiments of the first vertical shield 105 will bedesigned to extend above the head of the user, to prevent directradiation from reaching the user's head. The first vertical shield 105could be designed to extend above the head of a standing user, or insome circumstances a sitting user. The embodiment of the first verticalshield 105 shown has a length sufficient to extend from the head of thepatient to about the waist of the patient. Such a configuration isparticularly useful in procedures in which radiography is used tovisualize the patient's thoracic region. The length could be increasedto provide broader protection, but such increase in length must bebalanced with the additional weight and reduced flexibility inconfiguration that will accompany such changes.

In the illustrated embodiment an opening 110 is shown in the firstshielding means 105 to allow the patient's arm to extend from theshielded area. The opening 110 may optionally contain flexible shieldingmaterial such as a radiopaque curtain or flexible flanges 220. Theopening 110 as shown is semicircular, but may take any shape that allowsthe patient's appendage to extend through the shield. The opening 110presents a possible path for radiation leaks. The third shielding means120 is positioned to block radiation shining through the opening 110from irradiating the user. In the illustrated embodiment, the thirdshielding means 120 is a horizontal shield positioned over the opening110 and orthogonal to the first vertical shield 105. This particularconfiguration is useful to block radiation from an emitted positionbelow the opening 110 and on the side of the vertical shield opposite towhere the user is standing. The third shielding means 120 can beoriented differently to accommodate a different emitted positionrelative to the opening 110.

In the illustrated embodiment of FIGS. 1-3, the second shielding means115 is configured to rotate and translate relative to the firstshielding means 105 to allow the assembly 100 to be adjusted accordingto the dimensions of the patient and to allow the assembly 100 to bereconfigured to provide varying degrees of access to the patient andprotection from radiation. In the illustrated embodiment it takes theform of a second approximately vertical shield 115 connected to thesupport arm 150 so as to allow it to rotate about the longitudinal axisof the arm and translate parallel to the same longitudinal axis. In FIG.1 the second vertical shield 115 is shown in a position orthogonal tothe first vertical shield 105. Such a configuration is useful inpractice to give the user access to a patient's legs when the secondvertical shield 115 crosses the patient's body. It could also be loweredto the table 305 to form a complete shield if the patient is positionedwith the head closest to the second vertical shield 115. In FIG. 3 thesecond vertical shield 115 is shown generally parallel to the firstvertical shield 105.

The fourth shielding means 125 functions to block radiation that mightshine from under the second shielding means 115 when the secondshielding means 115 is positioned above the table 305. In theaccompanying figures the fourth shielding means 125 is shown as ahorizontal shield with a cutout 130. This trapezoidal cutout 130functions to provide access to a patient's groin during the procedure,which can be useful to allow access to the femoral vein for arthroscopicinsertion. The cutout 130 is a useful, but optional, feature of thesecond horizontal shield 125. In the illustrated embodiment the secondhorizontal shield 125 is positioned to intercept radiation emitted frombelow an operating table 305, but this structure could be positioneddifferently to intercept radiation from another direction.

The fifth shielding means 135, when present, functions to interceptradiation from exposing a user's lower body when the user is located onthe opposite side of the support arm 150 as the radiation source. Such astructure is not generally necessary below the first shielding means 150because operating tables typically are equipped with leaded curtainshanging from the operating table for procedures that requireradiological monitoring. However, the curtain does not always run theentire length of the table or extend along the width of the table.

Most of the surface area of the shielding means are opaque to thefrequencies and intensities of radiation which they are intended toblock. Some embodiments of the shielding means may be entirelyradiopaque. Exemplary materials that are radiopaque to X-rays includelead plates, lead filings, leaded acrylic glass, and polymer suspensionsof lead particles. Other heavy metals, such as barium, may be used,although lead has the advantage of a very high atomic number and stablenuclides. As thickness increases along the radiation vector radiopacityincreases. In designing the shielding means a balance will be struckbetween achieving adequate radiopacity and limiting the weight of theapparatus. For example, some embodiments of the lead shield will beabout 0.5-1.5 mm thick. Further embodiments of the lead shield will beabout 0.8-1.0 mm thick. Less dense materials, such as leaded acrylic,must be thicker to achieve the same level of radiopacity as lead. Forexample, some embodiments of the leaded acrylic shield will be about12-35 mm thick. Further embodiments of the leaded acrylic shield will beabout 18-22 mm thick. Lead barium type glass is another suitablematerial. For example, some embodiments of the lead barium type glassshield will be about 7-17 mm thick. Further embodiments of the leadbarium type glass shield will be about 7, 9, 14, or 17 mm thick.Comparing these exemplary materials, lead has the advantage of betterradiopacity per unit thickness, while leaded acrylic and lead bariumtype glass have the advantage of visual transparency and X-ray opacity.In some embodiments of the assembly 100 at least one of the firstthrough fifth shielding means 105, 115, 120, 125, 135 is transparent tovisible light. In such embodiments the transparent shielding means mayhave an optical transmissivity that equals or exceeds one of 50%, 55%,60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, and 100%.

Outside of the context of any specific material, the radiopacity of theshielding means can be expressed as millimeter-lead equivalents. Invarious embodiments of the system, at least one of the first 105, second115, third 120, fourth 125, or fifth shielding means 135 has aradiopacity of least 0.5 mm, 1.0 mm, 1.5, 2, 3, or 3.3 mm leadequivalent.

Any of the shielding means described above may be joined to one anotheror joined to the support means 145 via a radiopaque joint 205. Such aradiopaque joint 205 will minimize the transmission of radiation fromthe generator through the joint 205. This can be accomplished betweenplates for example by joining the plates with a sufficiently narrow gapthat a straight line cannot be traced from the radiation source throughthe gap when in position as intended at the operating table 305. Suchjoints 205 can be constructed using, for example, radiopaque braces orlap joints. A radiopaque joint 205 with a support arm 150 can beconstructed, for example, using a radiopaque sleeve around the supportarm 150 fastened to the shielding means.

The radiation shield assembly 100 is supported by the support arm 150and positioned to locate a first and second shield assembly between thepatient and the user. The first shield assembly is fastened to thesupport arm 150, comprising the first generally vertical shield 105 andthe first generally horizontal shield 120. The second shield assembly isalso fastened to the support arm 150 so as to rotate and translate alongthe longitudinal axis of the support arm 150 relative to the firstshield assembly. The second shield assembly comprises a second generallyplanar vertical shield 115 positioned above the table 305; a secondgenerally horizontal shield 125 connected to the second vertical shield115 and positioned above the table 305; and a lower generally planarvertical shield 135 extending from the second horizontal shield 125 tobelow the table 305. The second vertical shield 115 may be rotated aboutits axis to be approximately orthogonal to the longitudinal axis of thetable 305 or to be approximately parallel to the longitudinal axis ofthe table 305.

The shielding assembly may be part of a greater system comprising anoperating table 305, X-ray generator 310, and image intensifier 315 (seeFIGS. 10 and 11). The X-ray generator 310 will be positioned to directX-rays through the table 305 and to the image intensifier 315 on theother side, as is known in the art. The generator 310 and imageintensifier 315 may be mutually mounted on a C-arm 320, for example. Theoperating table 305 will frequently have a radiopaque curtain 325hanging from at least one side of the table 305. The curtain 325 mayalso extend around two or more sides of the table 305. The curtain 325is particularly useful when the system is configured with the X-raygenerator 310 below the table 305. The patient will generally be“prostrate,” meaning that the patient patent is lying on the table 305in any suitable orientation, including, supine, prone, and lying on theside. Conventionally the patient will be positioned on a table 305,between an X-ray generator 310 and an image intensifier 315, for exampleas commonly mounted on a C-arm 320. In the accompanying illustrationsthe X-ray generator 310 is shown below the patient, which is onecommonly used configuration, but not the only configuration in which thesystem could be used. The table (such as an operating table 305) iscapable of supporting the patient. Depending on the age and size of thepatient, various configurations of operating table 305 could be used.The image intensifier 315 will be positioned to receive X-rays projectedfrom the X-ray generator 310 (such as being positioned above the table305 if the X-ray generator 310 is below). Typically a radiopaque curtainshield 325 extends downwardly from the table 305 on the side one whichmedical personnel will be working (the “first side”). The firstshielding means 105 may be positioned to contact the table's edge alongits long dimension, or such that the bottom edge to the first shieldingmeans 105 is below the surface of the table 305 along its longdimension. The second shielding means 115 may also be positionedparallel to the long dimension of the table 305, so as to form a barrierbetween the user and the patient's lower extremities. In such aconfiguration the second shielding means 115 will also be positioned sothat its lower edge either contacts the table 305 or hangs below theelevation of the table's surface so as to block radiation from reachingthe user. Alternatively, the second shielding means 115 may be rotatedrelative to the first shielding means 105 at an approximately orthogonalangle, so as to cross the operating table 305 laterally. If the secondshielding means 115 has a cutout at the bottom to accommodate thepatient's body, this can provide the user access to the patient's lowerextremities, for example to gain access to the femoral vein. The secondshielding means 115 can be elevated along the support means 145appropriately to accommodate the patient's physiology. It is alsocontemplated that the second shielding means 115 could be positionedlaterally across the table 305, and in contact with the table 305, forexample if the patient's head is located proximate to the secondshielding means 115 (not shown). Thus a medical device, such as acatheter or an arthroscopy instrument, can be inserted into thepatient's vasculature through an arm or leg extending past the first 105or second shielding means 115 while minimizing the radiation thatreaches the user.

A method of radiology is provided, using any embodiment of the radiationshield assembly 100 disclosed above. The method comprises positioningany one of the radiation shield assemblies or systems above between apatient and a user, such that an appendage of the patient extendsthrough an appendage opening 110 in the shield assembly; inserting amedical device into vasculature of the appendage; and irradiating thepatient using a radiation generator 310 positioned such that radiationpasses at least partially through the patient while being blocked fromreaching the user by the shield assembly 100.

C. Example

Analysis was performed at the testing location for the purpose of theevaluation of an embodiment of the shielding system. Secondary scatteredradiation was created with two CIRS 76-125 patient equivalent phantomsusing a Siemens C-ARM X-ray source that was normally used forfluoroscopy operations. Analysis was performed to survey scatteredradiation through custom shielding and compared against no protectiveshielding versus lead apron results.

The test sample was a custom lead-acrylic radiation protective shieldfabricated specifically for C-ARM applications. The shielding consistsof a series of custom fabricated, 18.8 mm thick lead-acrylic material(Sharp Mfg. West Bridgewater, Mass.), having a minimum density of 4.36 gcm⁻³, a refractive index of 1.71, a thermal expansion coefficient of8E-6/° C. (30-380°), and a Knoop hardness of 370. Specifically, thematerial is lead barium type glass of high optical grade with greaterthan 60 percent heavy metal oxide, at least 55 percent PbO. The leadequivalency of this material is guaranteed by the manufacture to begreater than 3.3 mm Pb. The custom fabricated shielding design withlabels was constructed generally as shown in FIG. 4. With the exceptionof the support system which is made from aluminum, the shielding systemis entirely made from the exact same source material. All the panelswere fabricated and cut by the manufacturer.

Scattered radiation was created using a Siemens Model 10394668 withSerial No 1398 Medical C-ARM source through the CIRS 76-125 Lead-AcrylicPatient Equivalent Phantom extremity and torso used to represent apatient torso with an arm (Computerized Imaging Reference Systems, Inc.,Norfolk, Va.). The Siemens Medical C-ARM has a reported inherentfiltration of 0.8 mm Al at 70 kV along with the diamentor chamber, sizeB with 0.2 mm Al at 70 kV. No secondary filtration was used for themeasurements discussed in this report.

Radiation measurements were made using a Victoreen 470A Panoramic SurveyMeter with Serial No 2079. Calibration was performed using a Cs-137isotope source at the University of Alabama at Birmingham (UAB)Radiology Labs.

Comparisons with lead aprons were carried out using two products, aTechno Aide lead apron with serial no T116969, and a Xenolite withserial no 1 02 001. According to the manufactures' information, bothlead aprons have a lead equivalency of 0.5 mm Pb.

Test methods and procedures were guided by ASTM F3094 (ASTMInternational “Standard Test Method for Determining Protection Providedby X-ray Shielding Garments Used in Medical X-ray Fluoroscopy fromSources of Scattered X-Rays” ASTM Volume 11.03 Occupational Health andSafety; Protective Clothing (2017)), IEC 61331-1 (InternationalElectrotechnical Commission, “Protective devices against diagnosticmedical X-radiation—Part 1: Determination of attenuation properties ofmaterials” (2014) available athttps://webstore.iec.ch/publication/5289), and a medical physicist. Atesting methodology was developed and created prior to being performed.ASTM F3094 and IEC 61331-1 are incorporated herein by reference so as toenable a person of ordinary skill in the art to perform the protocols.

The custom fabricated lead-acrylic shielding was tested for theattenuation of scattered radiation as well as uniformity. In addition,measurements were made along the major edges of the total shield as wellas a semi-circular section where the physician will place the patient'sarm during procedure. Equivalent scattered radiation measurements werecompared against 0.5 mm lead equivalent lead aprons. The final set ofmeasurements were made with no shielding in place. All data was recordedon site. All measurements were recorded using a 10 second exposure timeand repeated at a minimal of three times. The criteria of protectionrating was based on the measured, scattered radiation attenuation froman 81 kV X-ray C-ARM source.

Radiation detected by the Victoreen 470A represents scattered X-rayradiation created by the interaction of X-rays with the CIRS 76-125patient equivalent phantom. The distance between the C-ARM X-ray sourcewas set at the default distance used for patient examinations of 17inches or 43.18 cm. This protocol is referred to herein as the “ModifiedASTM F3094/IEC 61331-1 Protocol.”

Average scattered radiation measurements made with no shielding can befound in Table 1 below. All measurements were made in triplicate at aminimal. Radiation measurements were first made with the custom,fabricated shielding in place so that the exact position of the shield,phantom, and detector could be marked for subsequent measurementswithout any shielding or comparison measurements with the two leadaprons.

TABLE 1 Summary of Phantom, Scattered Exposure without ProtectiveShielding Measurement Region mR/hr Avg (Std Dev) Centered 3.725 (0.095)Bottom, Edge 1.65 (0.1) Right, Edge 1.67 (0.057) Top, Edge 2.7 (0.0)Left, Edge 3.55 (0.057) Bottom, Left, Edge 2.267 (0.058)

All measurements were made in triplicate at a minimal. Average scatteredradiation measurements made with the custom, fabricated lead-acrylicshield (FIG. 12) can be found in Table 2 below. Measurements madethrough the custom fabricated shielding as well as currently acceptedlead aprons are very low intensity and only slightly above backgroundradiation. As a result, replicate measurements yielded a low standarddeviation as compared to measurements without any shielding in Table 1above.

TABLE 2 Summary of Phantom, Scattered Exposure with Custom FabricatedShielding Measurement Region mR/hr (Std Dev) Centered 0.083 (0.029)Bottom, Edge 0.15 (0.0) Right, Edge 0.15 (0.0) Top, Edge 0.15 (0.077)Left, Edge 0.2 (0.0) Bottom, Left, Edge 0.25 (0.0)

In addition, measurements were performed to detect the levels ofradiation in the precise position of the physician while in use.Measurements were specifically made at the physicians groin height aswell as the physician's chest height. The results are summarized belowin Table 3.

TABLE 3 Summary of Phantom, Scattered Exposure with Custom FabricatedShielding Measurement Region mR/hr (Std Dev) Physician Mid-Chest 0.0773(0.0343) Physician Groin  0.21 (0.022)

Scattered radiation measurements were then made with a Techno Aide 0.5mm lead equivalent apron and can be found in Table 4 below. Measurementswere made through a lead apron (FIG. 13) for the purpose of comparing anaccepted, medical radiation protective device to the one being proposedin this study. Strict comparison under actual, real-life positions wasused in an attempt to provide the most accurate information andcomparison. A graphical representation has been created below with Table4 summarizing the observed averages for scattered radiation measurementswith standard deviations.

TABLE 4 Summary of Phantom, Scattered Exposure with Techno Aide 0.5 mmPbLead Apron Measurement Region mR/hr (Std Dev) Centered 0.075 (0.027)Bottom, Edge 0.075 (0.029) Right, Edge 0.1125 (0.025) Top, Edge 0.1(0.0) Left, Edge 0.1 (0.0)

Once survey measurements had been completed on the first 0.5 mm leadequivalent apron, a second lead apron was selected and replicatemeasurements were performed exactly as done for the Techno Aide product.The measurements for average for scattered radiation measurements aresummarized below in Table 5 for the second, XenoLite lead aproncomparison.

TABLE 5 Summary of Phantom, Scattered Exposure with XenoLite 0.5 mmPbLead Apron Measurement Region Avg (Std Dev), mR/hr Centered 0.05 (0.0)Bottom, Edge 0.1 (0.0) Right, Edge 0.05 (0.0) Top, Edge 0.1 (0.0) Left,Edge 0.067 (0.03)

Two shield components were measured as a representative for uniformityto ensure that no voids are present in the overall shield apparatus.These measurements were performed in the same manner as described above.The results can be found in FIGS. 14 and 15. The data is represented inthe same format as in Tables 1-4 with the reported average scatteredradiation measurement values and standard deviation in parentheses.

As demonstrated by FIG. 14, no significant voids were observed whileperforming survey measurements of Main Panel A. Radiation measurementsyielded values very similar to previous measurements previously reportedfrom centering on individual panels. An additional note, replicatemeasurements were essentially identical and yielding a low standarddeviation.

As demonstrated by FIG. 15, the four regions were surveyed foruniformity with Main Body Panel A. The average measured radiation valueis represented above with the standard deviation in parenthesis. A quickcomparison between FIGS. 14 and 15 show very similar values between MainPanel A and Main Body Panel A.

Pass/fail criteria is based on the pre-accepted performance criteria ofindustrial grade lead-acrylic custom fabricated into a C-ARM shieldingapparatus. In addition, this shielding apparatus must provide protectionequal to or greater than currently, accepted lead aprons used for thesame application. Using the state of Alabama guide that a medical workerreceives no more than 5 Rem per year as a shallow dose equivalent andused as the pass/fail criteria.

This study endpoints are based on the successful completion of allmeasurements dictated by Alabama State guidelines for protective devicesused by physicians in C-ARM patient examinations. The study endpoint isspecifically based on comparable measurements made using currentlyaccepted lead aprons against no protective shielding of any kind versusthe custom fabricated lead-acrylic shielding.

The levels of radiation detectable behind the sponsoring custom,fabricated lead-acrylic shielding were consistent with calculated valuesbased on the manufacture's performance criteria. The levels of radiationdetected are within the maximum allowable permitted dose of radiationfor medical workers.

When compared to currently accepted lead aprons, relatively equal levelsof attenuated radiation were detected behind the custom shielding. Theperformance of the custom shielding and lead aprons is due in large partto the detection of secondary radiation in this case, as opposed toprimary radiation. Scatter equivalent primary radiation is used todetermine the official lead equivalency of a material. Under actualscatter conditions such as those used in this study, the measurableamount of secondary radiation is so low that one would not expectmeasurable differences between materials with different leadequivalency.

Using the currently accepted dose equivalent of 5 rems (R) per year, 52work-weeks a year, and 40-hours of exposure a week, total annualexposure with this shielding prototype was calculated. According to thehighest observed radiation measurements made during this study of 0.25mR/hr, a 40-hour work week would yield a total dose of 10 mR per week.Using the average value calculated from all measurements of 0.164 mR/hr,a 40-hour work-week would yield a total dose of 6.6 mR per week. Usingthe maximum possible dose of 10 mR per week, the custom fabricatedshielding apparatus would yield a total dose of 520 mR or 0.52 R annual.

D. Conclusion

The foregoing description illustrates and describes the processes,machines, manufactures, compositions of matter, and other teachings ofthe present disclosure. Additionally, the disclosure shows and describesonly certain embodiments of the processes, machines, manufactures,compositions of matter, and other teachings disclosed, but, as mentionedabove, it is to be understood that the teachings of the presentdisclosure are capable of use in various other combinations,modifications, and environments and is capable of changes ormodifications within the scope of the teachings as expressed herein,commensurate with the skill and/or knowledge of a person having ordinaryskill in the relevant art. The embodiments described hereinabove arefurther intended to explain certain best modes known of practicing theprocesses, machines, manufactures, compositions of matter, and otherteachings of the present disclosure and to enable others skilled in theart to utilize the teachings of the present disclosure in such, orother, embodiments and with the various modifications required by theparticular applications or uses. Accordingly, the processes, machines,manufactures, compositions of matter, and other teachings of the presentdisclosure are not intended to limit the exact embodiments and examplesdisclosed herein. Any section headings herein are provided only forconsistency with the suggestions of 37 C.F.R. § 1.77 or otherwise toprovide organizational queues. These headings shall not limit orcharacterize the invention(s) set forth herein.

What is claimed:
 1. A radiation shield assembly, configured to blockradiation emanating from a radiation source below a table for supportinga patient, the assembly comprising: (a) a supporting means to supportthe assembly, and configured to allow the assembly to translate relativeto the table to provide access to the patient; (b) a first shieldingmeans to block radiation from the source in a first approximatelyvertical plane, fastened to the supporting means, and (c) a secondshielding means to block radiation from the source in a secondapproximately vertical plane, fastened to the supporting means to allowthe second shielding means to translate and rotate along anapproximately vertical axis relative to the first shielding means;wherein the support means is configured to position the assembly suchthat a bottom edge of the first shielding means is about at the surfaceof the table and that a top edge of the first shielding means is atleast 175 cm (±20%) from the floor.
 2. The radiation shield assembly ofclaim 1, comprising an appendage opening dimensioned to allow a humanappendage to pass through the first shielding means; and a thirdshielding means to block radiation from the appendage opening in a firstapproximately horizontal plane that is approximately orthogonal to thefirst vertical plane, and fastened to the first shielding means suchthat the third shielding means translates and rotates with the firstshielding means.
 3. The radiation shield assembly of claim 1, comprisinga fourth shielding means to block radiation from the source in a secondapproximately horizontal plane that is approximately orthogonal to thesecond vertical plane, and fastened to the second shielding means suchthat the fourth shielding means translates and rotates with the secondshielding means.
 4. The radiation shield assembly of claim 1, comprisinga fifth shielding means to block radiation from the source in a thirdapproximately vertical plane that is approximately orthogonal to thesecond approximately vertical plane and to the second approximatelyhorizontal plane, connected to the second shielding means such that thefifth shielding means translates and rotates with the second shieldingmeans.
 5. The radiation shield assembly of claim 1, comprising a sixthshielding means to block radiation from the source in a fourthapproximately vertical plane that is approximately parallel to the firstapproximately vertical plane, wherein the sixth shielding means issecured to the first shielding means.
 6. The radiation shield assemblyclaim 1, comprising a sixth shielding means to block radiation from thesource in a fourth approximately vertical plane that is approximatelyparallel to the first approximately vertical plane, wherein the sixthshielding means is secured to the first shielding means, wherein thesixth shielding means is selected from the group consisting of: agenerally planar shield, a flexible drape, and an extension of the firstshielding means.
 7. The radiation shield assembly of claim 1, whereinthe first and the second shielding means are configured to rotaterelative to one another over an arc of from about 0- to about 180°. 8.The radiation shield assembly of claim 1, wherein the supporting meanscomprises an approximately vertical mast.
 9. The radiation shieldassembly of claim 1, wherein in operation the supporting means supportsthe entire weight of the radiation shield assembly.
 10. The radiationshield assembly of claim 2, wherein the first shielding means and thethird shielding means are configured to translate together vertically.11. The radiation shield assembly of claim 2, wherein the firstshielding means and the third shielding means are configured totranslate together along the support means.
 12. The radiation shieldassembly of claim 1, wherein at least one of the first and secondshielding means has a radiopacity of least 0.5 mm lead equivalent. 13.The radiation shield assembly of claim 1, wherein at least one of thefirst and second shielding means has a radiopacity of least 3 mm leadequivalent.
 14. The radiation shield assembly of claim 1, wherein atleast one of the first and second shielding means reduce radiationexposure by at least 85% when measured by the Modified ASTM F3094/IEC61331-1 Protocol.
 15. The radiation shield assembly of claim 1, whereinat least one of the first and second shielding means reduce radiationexposure to below 2.5 m R/hr when measured by the Modified ASTMF3094/IEC 61331-1 Protocol.
 16. The radiation shield assembly of claim1, comprising an appendage opening in the first shielding means and aflexible radiopaque member positioned to at least partially cover theappendage opening and configured to allow the human appendage to passthrough said appendage opening.
 17. The radiation shield assembly ofclaim 3, wherein the second shielding means and the fourth shieldingmeans are configured to translate together along the support means. 18.The radiation shield assembly of claim 1, wherein the support meanscomprises a mast supported by a floor stand.
 19. The radiation shieldassembly of claim 1, wherein the support means is a mast that issuspended by an overhead boom.
 20. The radiation shield assembly ofclaim 1, wherein at least one of the first and second shielding means istransparent to visible light.
 21. The radiation shield assembly of claim1: (a) wherein the first shielding means is a first generally planarvertical shield; (b) comprising an appendage opening dimensioned toallow a human appendage to pass through the first shielding means and afirst approximately horizontal shield to block radiation from theappendage opening in a first approximately horizontal plane that isapproximately orthogonal to the first vertical plane, and fastened tothe first shielding means such that the first approximately horizontalshield translates and rotates with the first shielding means; (c)wherein the second shielding means is a second generally planar verticalshield; (d) comprising a second approximately horizontal shield to blockradiation from the source in a second approximately horizontal planethat is approximately orthogonal to the second vertical plane, andfastened to the second shielding means such that the second generallyplanar vertical shield translates and rotates with the second shieldingmeans; and (e) comprising a lower generally planar vertical shield toblock radiation from the source in a third approximately vertical planethat is approximately orthogonal to the second approximately verticalplane and to the second approximately horizontal plane, connected to thesecond shielding means such that the lower generally planar verticalshield translates and rotates with the second shielding means.
 22. Theradiation shield assembly of claim 1, wherein the support means isconfigured to position the assembly such that a bottom edge of the firstshielding means is about at the surface of the table and that a top edgeof the first shielding means is at least about 190 (±20%) cm from thefloor.